Hierarchical Bus Arbiter with Dynamic Priority and Credit Allocation
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Solution Overview
Problem
Conventional bus channel allocation methods, such as round-robin and fixed priority-based algorithms, fail to efficiently utilize bandwidth and can lead to starvation of master devices with lower priorities, resulting in degraded performance.
Innovation Solution
A hierarchical bus channel bandwidth allocation method that allocates a portion of time slices to priority-based allocation and another portion to credit-based allocation, allowing for dynamic adjustment based on application requirements, thereby ensuring each master device receives sufficient access to complete time-sensitive tasks and preventing starvation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fixed priority-based allocation is used, then high priority master devices can access the bus channel efficiently, but low priority master devices may be starved and not receive sufficient access
Solution Approach 1:
The patent implements dynamic priority adjustment where the arbiter monitors bus access patterns and dynamically modifies priority levels. Low priority devices that experience starvation can have their priorities elevated, while high priority devices that have received sufficient access can have their priorities reduced. This dynamic adjustment resolves the contradiction by maintaining both efficient bandwidth utilization and fairness to low priority devices.
Solution Approach 2:
The arbiter incorporates feedback mechanisms that monitor the access status of all master devices. When a low priority device fails to access the bus for a certain period, this feedback triggers a priority adjustment. The system continuously adapts priority assignments based on actual bus usage patterns, ensuring both high overall utilization and adequate access for all devices.
2Reliability
If round-robin allocation is used, then all master devices receive equal access opportunities, but the system cannot distinguish the relative importance of requests and time-sensitive tasks may not be completed timely
Solution Approach 1:
The system dynamically adjusts the round-robin cycle and priority levels based on real-time bus utilization and request characteristics. When time-sensitive tasks are detected, the arbiter can shorten the round-robin cycle for those specific devices or temporarily elevate their priority, thus maintaining fairness while improving responsiveness to critical tasks.
Solution Approach 2:
The arbiter changes operational parameters such as round-robin cycle duration, priority levels, and time slice allocations based on system conditions. For time-sensitive tasks, parameters are adjusted to provide faster access, while maintaining overall fairness through controlled parameter changes rather than static allocation.
3Reliability
If weighted round robin arbitration is used, then credit-based allocation can prevent starvation, but the system becomes complex and high credit devices can monopolize the bus for long durations
Solution Approach 1:
The patent extracts the credit management complexity from the arbitration decision-making process. Instead of using complex weighted round-robin with credit tracking for all devices, the system uses simplified credit-based access only when needed, combined with dynamic priority adjustment. This reduces overall system complexity while maintaining the starvation prevention benefit.
Solution Approach 2:
The system dynamically switches between different arbitration modes and adjusts credit allocation based on actual bus usage. Rather than static weighted round-robin, the arbiter adapts credit assignments and arbitration strategies in real-time, preventing monopolization while maintaining simplicity through dynamic rather than static complexity.
Data Source
AI summary
A method for bandwidth allocation includes receiving requests for bus channel access from two or more master devices. Next, the method selects one of priority-based allocation or credit-based allocation. Upon selecting the priority-based allocation, the method grants bus channel access based on pre-assigned priorities for bus channel access. Upon selecting credit-based allocation, the method grants bus channel access based on pre-allocated credits for bus channel access, and the method decrements the credit from the master device that has been granted bus channel access.